1. Field of the Invention
The present invention relates to a mounting device and method and, more particularly, mounting arrangements for apparatus subject to dynamic forces.
2. Description of the Prior Art
An expansion or movement joint generally comprises an air gap between two building codes units. The gap permits relative movement between the building units to avoid damage to the building made up of the building units when the building units move relative to each other. Such movement can result from, for example, temperature variations, expansion, shrinking or settling of the ground. The expansion joint can be covered or filled with a resilient material if desired.
One application of such expansion joints is between block foundations, which are embedded in the ground, and the surrounding building parts, such as concrete floors, columns or walls. Another is between the structure supporting a machine which develops large dynamic forces and the floor surrounding the machine. Such an expansion joint both avoids detrimental movements of the floor structure due to movements of the machine and prevents the spread of vibrations from the machine to adjacent building. An expansion joint for this purpose can also be filled or covered with resilient material. Typically, such a joint is an air gap 2-5 centimeters wide around the machine foundation.
The provision of expansion joints around the foundations of machines which develop large dynamic forces is recommended by leading experts. See E. Rausch, "Maschinenfundamente und Andere Dynamisch Beanspruchte Baukonstruktionen", VDI-Verlag GmbH, Dusseldorf 1959; D.D. Barkan, "Dynamics of Bases and Foundations", p. 133, 245,McGraw-Hill Book Co.; and P. Srinivasulu and C.V. Vaidyanathan, "Handbook of Machine Foundations", p. 74, 136, 213, McGraw-Hill Book Co., NY 1978. In addition many countries have building that require expansion joints around machine foundations.
Recent technical developments have resulted in stronger machines, while buildings are becoming less sturdy because the higher-quality building materials being used have less dynamic stiffness and provide reduced damping. Moreover, there is a tendency towards larger and larger industrial plants and increasingly close positioning of machinery. These developments have contributed to an increase of the number of cases of structural damage due to vibration. It has even been found that, in extreme cases, prior art expansion joints have had an effect directly contrary to the desired one, by actually contributing to an increase of the vibration levels in the adjacent, statically loaded, parts of the building housing the machinery.